Present invention relates to a method for analyzing a telecommunications system and more specifically to a method for determining available bandwidth in a fast packet network for including voice traffic.
As the use of data networks has increased in recent times, a number of technologies have been developed to increase the speed at which data is transmitted. One technology is fast packet switching which provides the capability of transmitting data, digitized voice and digitized image information. It makes use of short, fixed length packets (or cells). The underlying switching technology is based on the statistical multiplexing of data and voice in fixed length cells. Any of these packets could carry digital voice, data or digital image information. Fast packet is an effective way of making best use of available bandwidth. It offers the benefits of conventional multiplexing techniques and circuit switching techniques. Fast packet switching may be performed in number of different ways. Two examples of this type of switching are frame relay and asynchronous transfer mode (ATM).
Frame relay is a frame-based transmission technique designed to create more efficient networks by permitting users to access only the amount of bandwidth they need for a given application. The frame relay is a xe2x80x9cconnection orientedxe2x80x9d protocol. It establishes a logical connection for the duration of the transmission and may be implemented as a permanent virtual circuit (PVC) service. The frame relay network provides logical connectivity between geographically distributed devices, using special circuits, which can be multiplexed over a single access path. Disclosed in FIG. 1b is a portion of a data network which may be employed by an enterprise which incorporates the use of frame relay. The user interfaces receive and transmit information to the frame relay network 24 through the frame relay assembler-disassembler (FRAD) device 22.
ATM is a cell-based data transfer technique in which channel demand determines packet allocation. This network technology is based on transferring data in cells or packets of a fixed size. The cell used with ATM is relatively small compared to units used with other technologies. The small, constant cell size allows ATM equipment to transmit video, audio, and computer data over the same network, and assure that no single type of data occupies the majority of the available bandwidth.
One application for fast packet technology is in the area of telephony. Many businesses currently have their own internal phone system for routing internal calls. One type of internal system is the private branch exchange (PBX) which is a private phone network employed within an enterprise. Users of the PBX system share a certain number of outside lines for making and receiving calls external to the PBX system, while calls made within the system are simplified because the number used to connect is typically just three or four digits. Disclosed in FIG. 1a is a typical PBX phone system which includes a number of telephones 10 connected to the line side of the PBX system 12 and network connections established to the trunk side. Additionally, there are PBX tie trunks which tie into other PBX systems which may be remotely located.
A variety of devices currently exist for providing the integration of voice traffic, typically facilitated by PBX systems into new and existing fast packet networks. Although fast packet networks were originally designed for the efficient transmission of high speed packet data only, advances in technology now allow the efficient transmission of voice traffic, typically compressed well below the traditional 56/64 kbps voice channel. Such arrangements allow, for example, a frame relay customer with multiple geographically dispersed locations to carry in-network voice traffic without the expense of accessing the PSTN and without the expense of accessing an interexchange long distance carrier.
The inventor has recognized that when combining a traditional voice network and a frame relay and/or a asynchronous transfer mode (ATM) system, certain tools may be required in order to perform analysis to determine if the network is capable of carrying voice traffic. Described herein is a systematic approach for converting a quantified voice traffic volume expressed in terms of hours or minutes or usage per defined period of time or busy hour Centum Calling Seconds (CCS) into an equivalent frame relay or ATM packet data payload.
In the invention described herein, a method is disclosed for calculating the bandwidth necessary in order for a fast packet network such as a frame relay or an asynchronous transfer mode (ATM) system to carry voice traffic. The analysis for calculating bandwidth may be based upon input from three different sources. A first source may be usage criteria for the telephone system which is to employ the fast packet network. This criteria is predicated upon deriving a resultant packet bandwidth based upon input expressed in terms of time. These units of time may be minutes or hours of use per month. An additional factor for the usage criteria is the percentage of the customer""s traffic which may appear during the busy hour, i.e. the time of the day when voice traffic may be the highest. These separate inputs may be mathematically combined in order to define a usage criteria.
Another input which may be used in the analysis is the station criteria. The station criteria may be the estimated or actual quantity of voice stations as input into a telephone system. The station criteria may be predicated upon deriving a resultant packet bandwidth based upon inputs expressed in terms of number of stations (telephones) originating and terminating telecommunications traffic and a determined volume of traffic usage per station during a particular period of time. A mathematical combination of these inputs may determine a station criteria.
The next step in determining the bandwidth is using either the usage or station criteria to determine an equivalent number of trunks for the telephone system. A number of different theorems may be applied to these input criteria such as Poisson, Erlang, or an historical table in order to convert the various usage or station criteria into an equivalent number of trunks. If the specifications of the telephone system at issue are known, a trunk criteria, which is the actual number of trunks, may be employed in the analysis.
Once the equivalent or actual number of trunks is known, it is now possible to determine a bandwidth which will be required in order for the fast packet network to carry voice communications. A compression factor is applied to the equation at this point and through this compression factor, an available bandwidth for the fast packet system is determined.
Numerous modifications and additions will be apparent to those skilled in the art upon further consideration of the invention.